Because of the recent increase in health consciousness, sugar-free and low- or non-calorie foods and drinks are desired. These foods and drinks have health benefits such as promotion of dieting, prevention of obesity, prevention of tooth decay and the like, but still need to have some sweetness in order to taste good. Substances known as providing sweetness include sugar alcohols and high-intensity sweeteners (also referred to as “artificial sweeteners”), which are described in many study reports. The sugar alcohols and high-intensity sweeteners are often used for the above-mentioned foods and drinks as substitutes of sugar in order to increase the sweetness, but are reputed to have disadvantages that sugar does not have. For example, the sugar alcohols and high-intensity sweeteners do not provide depth or thickness in taste and have heavy aftertaste and astringency.
Conventionally, foods and drinks are devised in many ways to taste better. One such way is to put additives. Additives which are, for example, effective to provide thickness in taste and alleviate aftertaste and astringency have been reported. For example, hesperidin glycoside (patent document 1: Japanese Laid-Open Patent Publication No. 11-318379) and theanine, which is an ingredient of tea (patent document 2: Japanese Laid-Open Patent Publication No. 9-313129), have been reported as additives which provide a satisfactory flavor to foods or drinks.
The former flavor improving agent has an effect of reducing the heavy aftertaste but does not sufficiently alleviate the astringency and does not sufficiently provide depth or thickness in taste. Thus, the improving effect thereof is not satisfactory. The latter flavor improving agent is applicable to a wide range of foods and drinks but does not have a sufficient flavor improving effect.